Result Simple Perl

Result::Simple - Tuple-based Error Handling

Result::Simple provides lightweight error handling using tuples ($value, $error) instead of objects.

Core Functions

ok($value) / err($error)

use Result::Simple qw(ok err);

sub divide {
    my ($a, $b) = @_;
    return err('Division by zero') if $b == 0;
    return ok($a / $b);
}

my ($result, $error) = divide(10, 2);
if ($error) {
    warn "Error: $error";
} else {
    print "Result: $result";
}

Practical Examples

Error Chaining Pattern

sub process_config {
    my $filename = shift;
    
    my ($content, $read_error) = read_file($filename);
    return (undef, $read_error) if $read_error;
    
    my $data = eval { decode_json($content) };
    return err("JSON error: $@") if $@;
    
    return ok($data);
}

Type Checking with result_for

use Result::Simple qw(ok err result_for);
use Types::Standard qw(Dict Str);
use Types::Common::Numeric qw(PositiveInt);
use kura Error => Dict[message => Str];

# result_for requires structured error type (not plain string)
result_for calculate => PositiveInt, Error;

sub calculate {
    my ($a, $b) = @_;
    # Error must be structured (HashRef)
    return err({ message => 'Invalid input' }) if $a < 0;
    return ok($a * $b);
}

# Set RESULT_SIMPLE_CHECK_ENABLED=1 to activate type checking
# $ENV{RESULT_SIMPLE_CHECK_ENABLED} = 1;

my ($result, $error) = calculate(5, 3);
if ($error) {
    warn "Error: $error->{message}";
} else {
    print "Result: $result";  # 15
}

# Type checking works when RESULT_SIMPLE_CHECK_ENABLED=1
# calculate(5.5, 3);  # Dies: Invalid success result (Float instead of PositiveInt)

Important: result_for requires:

• Type::Tiny objects (not string type names)
• Structured error type (use Dict[...] with kura)
• Environment variable RESULT_SIMPLE_CHECK_ENABLED=1 for runtime checking